1. Field of the Invention
The present invention relates to a container opener for opening/closing a sealable container for containing and transferring a plurality of semiconductor wafers oriented horizontally and arranged in layers at predetermined intervals. More particularly, the invention relates to a front opening unified pod (FOUP) opener configured such that a clean atmosphere is not contaminated with dust adhering to a FOUP door and a portion of the FOUP opener exposed to an ambient atmosphere.
2. Description of the Related Art
When dust or an evaporated organic substance (hereinafter collectively called xe2x80x9cdustxe2x80x9d) adheres to the surface of a semiconductor wafer; i.e., when a wafer is contaminated with dust, the yield of products; i.e., the nondefective product percentage, is impaired. Thus, wafers must be maintained at a high level of cleanliness; wafers must be transferred or processed in a highly clean environment.
Wafers are generally processed in a clean room, whose cleanliness is high. Also, wafers are conveyed while being contained in a sealed FOUP, whose interior is maintained at a high level of cleanliness. Such a FOUP enables conveyance of wafers via a room of low cleanliness or the outdoors; i.e., a FOUP can protect wafers from contamination with dust during conveyance via such places.
A FOUP opener is disposed at the interface between the interior and exterior of a clean room. The FOUP opener includes a port plate having an opening portion, which can be opened/closed, and a port door for opening/closing the opening portion. A FOUP has a door (a FOUP door), which faces the opening portion of the port plate. When wafers are to be unloaded from a space maintained at a high level of cleanliness (a first control space) within the FOUP in order to undergo processing steps, the FOUP door is opened. Unloaded wafers are robotically conveyed within a wafer transfer space (a second control space) maintained at a high level of cleanliness similar to that in a processing chamber, and then transferred into a clean room, which serves as a processing chamber. Processed wafers are returned from the clean room to the high-cleanliness space within the FOUP via the wafer transfer space. Thus, wafers are moved through the opening portion of the port plate.
When no wafer is moved, the opening portion of the port plate is closed by means of the port door. The port door includes a detachment/attachment mechanism for latching the FOUP door to a FOUP body (a FOUP frame) or unlatching the FOUP door from the FOUP frame by means of a latch mechanism, and a holder mechanism for holding the FOUP door. The detachment/attachment mechanism includes a latch key for detachment/attachment use, and the holder mechanism includes a vacuum chuck pad for holding use.
As mentioned above, wafers are moved between the FOUP and the clean room, which serves as a processing chamber, via the opening portion of the port plate and the wafer transfer space. In the course of the movement, a highly clean environment must be maintained, and wafers must be protected from contamination with dust. Thus, entry of dust into a clean room serving as the wafer transfer space must be prevented. Dust which possibly enters the clean room includes dust suspended in a space of low cleanliness (an ambient atmosphere) outside the clean room, dust adhering to the FOUP (particularly the outside wall of the FOUP door), dust adhering to the outside wall of the port door exposed to the exterior of the clean room, and dust generated as a result of opening/closing of the FOUP door (dust generated as a result of operation of the latch key for detachment/attachment use and the vacuum chuck pad for holding use).
As shown in FIG. 6, a conventional FOUP opener vacuum chucks and holds a FOUP door 013 merely by means of two upper and lower vacuum chuck pads 024 provided on the outside wall of a port door 023, the outside wall facing a FOUP (i.e., the outside wall being exposed to the exterior of a clean room). Thus, the FOUP door 013 is opened/closed (detached from or attached to a FOUP frame) while dust is caught in a space 090 between the outside wall of the FOUP door 013 and the outside wall of the port door 023. Reference numeral 025 denotes a latch key for detachment/attachment use provided on the port door 023, and reference numeral 015 denotes a keyway into which the latch key 025 is inserted.
However, since the space 090 is not sealed, the clean room is contaminated as a result of scattering of contaminated air present in the space 090 (an ambient atmosphere caught in the space 090), dust adhering to the outside wall of the FOUP door 013, dust adhering to the outside wall of the port door 023, and dust generated as a result of opening/closing of the FOUP door 013 (dust generated as a result of operation of the latch key 025 for detachment/attachment use and vacuum chuck pads 024 for holding use), thus causing contamination of wafers with dust. Once the clean room is contaminated, restoration of cleanliness within the clean room to a regular, high level consumes a considerably great amount of time and involves incurrence of cost.
An object of the present invention is to provide a FOUP opener capable of minimizing the possibility of contamination of wafers with dust when a port door vacuum-chucks and holds a FOUP door at the time of opening of a FOUP in order to unload wafers from inside the FOUP for subjecting the wafers to processing, through prevention of entry, into a clean room, of contaminated air present in a space between the outside wall of the FOUP door and the outside wall of the port door facing the FOUP (the outside wall exposed to the exterior of the clean room), dust adhering to the outside wall of the FOUP door, dust adhering to the outside wall of the port door, and dust generated as a result of opening/closing of the FOUP door (dust generated as a result of operation of a latch key for detachment/attachment use and vacuum chuck pads for holding use).
To achieve the above object, the present invention provides a FOUP opener for opening and closing a FOUP door which closes a front opening portion of a FOUP containing a plurality of semiconductor wafers oriented horizontally and arranged in layers at predetermined intervals, the FOUP opener comprising a dock plate for carrying and positioning the FOUP; a dock moving mechanism for moving the dock plate to a position for detachment and attachment of the FOUP door; a port door including a detachment/attachment mechanism for detaching and attaching the FOUP door and a holder mechanism for holding the FOUP door; a port plate including an opening portion, the opening portion being closed by the port door; a port door horizontal-movement mechanism for horizontally moving the port door; and a port door vertical-movement mechanism for vertically moving the port door with the port door holding the FOUP door, so as to house the FOUP door, wherein the port door includes sealing means for sealing a space defined between an outside wall of the FOUP door and an outside wall of the port door.
Thus, the sealing means provided on the port door can seal the space defined between the outside wall of the FOUP door and the outside wall of the port door facing the FOUP (the outside wall exposed to the exterior of the clean room), and extending over substantially the entire outside wall of the FOUP door.
As a result, when the port door vacuum-chucks and holds the FOUP door at the time of opening of the FOUP in order to unload wafers from inside the FOUP for subjecting the wafers to processing, there is prevented entry, into the clean room, of contaminated air present in the space between the outside wall of the FOUP door and the outside wall of the port door facing the FOUP (an ambient atmosphere caught in the space), dust adhering to the outsidewall of the FOUP door, dust adhering to the outside wall of the port door, and dust generated as a result of opening/closing of the FOUP door (dust generated as a result of operation of the latch key for detachment/attachment use and vacuum chuck pads for holding use), thereby minimizing the possibility of contamination of wafers with dust. Thus, the clean room can be readily maintained at a high level of cleanliness in an economical manner in terms of time and cost.
Generally, the FOUP door is made of resin, and the port door is made of metal. When the resin FOUP door is vacuum-chucked and held by the vacuum chuck pads provided on the port door to thereby define a sealed space between the outside wall of the FOUP door and the outside wall of the port door facing the FOUP, the resin FOUP door exhibits intimate contact with a sealing means portion of the port door to thereby be held tight, thereby enhancing the degree of sealing of the sealed space. Thus, the possibility of contamination of wafers with dust is reduced, and the maintenance of the clean room at a high level of cleanliness can be facilitated.
Preferably, the sealing means assumes the form of a protrusion provided along the outer circumferential edge of the port door in such a manner as to project toward the FOUP door and to abut the FOUP door along the entire circumference of the FOUP door.
Thus, by means of a relatively simple structure, there can be effectively sealed the space defined between the outside wall of the FOUP door and the outside wall of the port door facing the FOUP, and extending over substantially the entire outside wall of the FOUP door.
Preferably, the sealing means comprises a packing member.
Employment of the packing member enhances the degree of sealing of the sealed space defined between the outside wall of the FOUP door and the outside wall of the port door facing the FOUP, thereby further reducing the possibility of contamination of wafers with dust and facilitating the maintenance of the clean room at a high level of cleanliness.
Preferably, the FOUP opener further comprises evacuation means for evacuating a contaminated atmosphere from the sealed space defined between the outside wall of the FOUP door and the outside wall of the port door.
As a result, since contaminated air or dust can be forcibly evacuated to the exterior of the clean room from the sealed space defined between the outside wall of the FOUP door and the outside wall of the port door, the degree of sealing of the sealed space is further enhanced. Thus, entry of contaminated air or dust into the clean room from the sealed space can be completely prevented, thereby still further reducing the possibility of contamination of wafers with dust and facilitating the maintenance of the clean room at a high level of cleanliness.